For bugs that result from Mozilla build problems. ("Building" is the process of converting the thousands of Mozilla source code files into a actual executable software.) If a file in a newly-downloaded build is missing or corrupted, file the bug in this component.

Documenting the reason for followup:
Followup needs to address the "objdir" field in mozharness/single_locale/thunderbird.py. It has to be set to "obj-firefox" right now for unittests. We have it set to obj-thunderbird for the build steps, and it should be the same here.